(1) Field of the Invention
The invention is in the field of quick change tool chucks and tools therefor.
(2) Description of the Prior Art
The prior art includes many efforts to satisfy the need for a quick change tool chuck. One effort is shown in Emrick U.S. Pat. No. 1,862,337 which discloses a chuck consisting of a tubular chuck body having a lower end portion reduced to form a shoulder upon which a spring seats. The spring operates upon a collar slidable on the reduced portion of the body and carries a tubular housing which encloses the spring and fits upon the enlarged upper end of the body. Coupled with the upper end of the body is a spindle and in the lower end of the body is a tool bit receiving bore. A dog or key member is supported in a radial aperture formed in the reduced extension of the chuck body. The key member has inwardly projecting teeth on its inner surface which extend into the bore to support the tool.
Another prior art effort is shown in Palmgren U.S. Pat. No. 2,172,070 which discloses a chuck in association with a tapering shank which is nonrotatably secured to an elongate adapter having a bore. The sleeve of the chuck provides a housing for the head end of the adapter, the sleeve having a sliding fit with respect thereto which permits rotation of the adapter while the sleeve remains stationary. The adapter provides a shoulder against which a coil spring seats. The coil spring encircles the adapter and is confined within the sleeve by a roller bearing. A tool retaining member is secured axially inside the sleeve. The retaining member is provided with three slots extending lengthwise. The slots receive three triangularly-shaped jaws which clamp the tool bit within the retaining member. The tapering outer edge of each jaw conforms to the tapering inner surface of the adapter. The gripping jaws are forced inwardly by the adapter wall to grip the tool shank. The gripping jaws are provided with an expanding ring which will cause outward movement of the gripping jaws to allow insertion of the tool shank.
Another prior art effort is the commercially-available quick change drill and drill chuck system called the Quick Change Adapter System (Model PB-102) made by the Precision Twist Drill Division of PTD Inc. in Crystal Lake, Illinois. The present invention provides solutions to several problems encountered with that system. First, the tools used in the present invention do not require an adapter to fit in the chuck. The present invention requires only a minor grind on the tool shank. This represents a significant reduction in cost. Second, the present invention eliminates the stocking, storage, and handling problems which are inherent in the prior art design of the adapted drills. And third, in the present invention the tool shank is held positively (clamped securely) in the chuck which eliminates the drill runout caused by the sliding adapted drills in the quick change chuck of that prior art system.